Electrocardiograph vector plotter



R..J. BALHRN ET AL LECTROCARDIOGRAPH VECTOR PLTTER Dec. 16., 1969 Filed Oct.

INVENTOR' m /f/ LEAL HORN w MAX/0 l. HER/PERA Mge-h MM ATTORNEYJ United States Patent O ELECTROCARDIOGRAPH VECTOR PLOTTER Robert J. Balhorn and Mario I. Herrera, Aberdeen,

S. Dak., assignors to Medical Devices Corporation, Aberdeen, S. Dak.

Filed Oct. 4, 1968, Ser. No. 765,126 Int. Cl. Gille 21/20; Gtllv 1/30; G09d 29/10 U.S. Cl. 33-1 5 Claims ABSTRACT F THE DISCLOSURE A plotter for the resultant vector of electric potential obtained from cardiographic leads according to the Einthoven system has an equilateral triangle with perpendicular lines representing values constituting a grid extending between its sides, appropriate indicia along the sides and polar indicia circurnscribed around the triangle, and a movable indicator which pivots about the center ofthe triangle.

BACKGROUND OF THE INVENTION Field of the invention The invention relates to electrocardiographs and more particularly to their analysis by determination of the direction and magnitude of resultant force, which can be represented by a vector. As stated by Dr. Paul Wood in Diseases of the Heart and Circulation, London, 1957, pages 89-96, the maximum potential differences within the heart at any given moment may be represented in magnitude and direction by a line of appropriate length and direction. The magnitude and direction of this vector change during the phases of ventricular excitation and recovery but may be resolved into mean values. The magnitude and direction of the vector may be obtained at any moment from the electrocardiograms obtained from any two (or three) of the standard electrocardiographic leads, the standard leads being connected to the left arm, the right arm, and the left leg. The resultant vector, if projected on the sides of an equilateral triangle, the apices of which are represented by the left and right arms and by the left leg, represents along the sides of the triangle the values of the voltages. Hence by plotting the values of the voltages of any two of the leads along the sides of the triangle and projecting them inwardly, the resultant vector may be obtained.

Instead of plotting the voltages along the sides of an equilateral triangle, these may be plotted along a triaxial reference system which represents the three sides of the triangle transposed so that they intersect at a common point. The lines then represent the voltages from the three leads.

While the direction of the resultant vector varies, its mean axis or average has signiicance to the medical profession in examination and diagnosis.

The present invention is a tool by means of which the resultant vector may be easily and quickly computed thereby avoiding the necessity and the inherent inaccuracy involved in the laborious manual plotting ot the readings from an electrocardiogram.

Description of the prior art While various plotting devices are known, none adapted for the purposes of the present invention is known.

SUMMARY OF THE INVENTION Briefly stated, the present invention includes a graphic representation of an equilateral triangle, or triaxial system, with grids and indicia corresponding to those commonly used in electrocardiography, a movable indicator,

3,483,621 Patented Dec. 16, 1969 ICC and additional indicia representing the direction or axis of the resultant vector.

BRIEF DESCRIPTION OF THE DRAWING FIG. l of the drawing illustrates a plotter of the type used in the Einthoven system;

FIG. 2 represents a plotter of the type used in the Hexaxial system; and

FIG. 3 is a section on the line 3-3 of FIG. 1 of an embodiment in which a plotter of each type is on opposite faces of a single instrument.

With reference to FIG. l, the plotter illustrated includes a base 10, which, for portability, is preferably of relatively stiff sheet material although the indicia which will be described may obviously be applied to any appropriate surface whether portable or fixed.

The sheet has applied to it indicia including an equilateral triangle with a first side 11, a second side 12, and a thir-d side 13. These are indicated by the indicia I, II, and III respectively, indicating the values obtained from the first, second, and third standard electrocardiographic leads.

In order to orient the resultant vector which will be obtained, conventional polar indicia 15 are circumscribed about the center of the triangle, the horizontal axis 16 being parallel to side 11 of the triangle. In accordance with conventional practice, the midpoint of each of the sides of the triangle represents the origin or zero, the positive values on side I extending to the right and those on sides II and III extending in a direction away from the horizontal axis 16. Numerical indicia 18 indicating positive and negative values are applied along each side of the triangle, representative of voltage values.

Side 11 has grid lines 20 extending perpendicularly therefrom. Similarly, sides 12 and 13 have grid lines 21 and 22 respectively extending perpendicularly from each. These permit the plotting of the values from each lead along the appropriate side and the projection inwardly in order to determine the resultant vector.

As an example and as represented on the drawing, assume that values are obtained as follows: Lead I, plus 5; Lead II, plus l0; Lead III, plus 5, Plotting these, as indicated, produces a resultant vector of plus 60. In order that the resultant vector may be easily determined, a movable indicator 25 is pivotally mounted on the face of the device about the center of the triangle. The indicator is preferably of transparent plastic and has a reference line 26 which intersects the center of the triangle. It will be seen that in solving the problem described, one need only move the indicator until the reference line intersects the intersection of the projection of any two of the values obtained from the two leads. Then the polar or angular position of the axis may be instantly read from the indicia circumscribed around the triangle.

The modication of FIG. 2 indicates a similar type instrument which employs the hexaxial system. This instrument likewise may be mounted on a base 30 and has lines 31, 32 and 33 representing the three standard electrocardiographic leads. These intersect at an axis 34 and are arranged triaxially or at 60 polar intervals. The lines are indicated by the characters I, II and III representing the three standard leads, line 31 constituting the horizontal reference line.

Grid lines 4l), 41 and 42 project perpendicularly from reference lines 31, 32 and 33 respectively and at spaced intervals convenient for representing electrocardiographic values. Numerical indicia 48 are applied to represent such values. In accordance with practice, values to the right of the axis on line 31 are indicated at positive and those at the lett negative. Values below line 31 on lines 32 and 33 are indicated as positive and those above as negative.

Polar indicia are indicated as having their origin with the intersection of line 31 at the right of the axis 34 and extend to minus 180 above the line 31 and to plus 180 below the said line.

As an example of the use of the device, assume value from leads to be as follows: Lead I, 5; Lead II, 10; Lead lII, 5. Plotting these as indicated results in a reference vector having a bearing of plus 60. The device is provided with a movable indicator 55 having a reference line 56 and mounted for rotation about the axis, the reference line intersecting the axis. The problem indicated is solved by moving the indicator until the reference line intersects any two of the above projected Values.

The device described may be made in various sizes in various materials depending upon the desired use. It may be made on sheet material of a size to be easily carried, or may be enlarged for classroom or teaching purposes. If desired, a single instrument may have representations according to FIGS. 1 and 2 on its opposite sides. In this embodiment the indicators may be carried by a shaft 27 which extends through the base 10.

What is claimed is:

1. An electrocardiograph vector plotter comprising a relatively fiat surface, an equilateral triangle on said surface, polar angle representations circumscribing said triangle and having as an axis the center thereof, said triangle having indicia along its sides and grid lines extending perpendicularly inwardly from each of its sides, the midpont of each of the sides indicating an origin point, a first horizontal side having an indication of positive indicia to the right of the origin and negative indicia to the left of the orgin, and second and third sides having an indication of negative indicia therealong adjacent to the first side and positive indicia extending from each of thier origin points downwardly, and polar indicia circumscribing said triandle, said polar indicia having an origin point at the intersection with the right side of a horizontal line extending through the axis of the triangle and indicating 0 to minus 180 above said line and 0 to plus 180 below said line, and an indicator pivotally mounted on said surface at said axis and having an indicator line adapted to line up said axis with the intersection of any two or three grid lines and to indicate the polar bearing of said line.

2. An electrocardiograph vector plotter comprising a surface, an equilateral triangle on said surface, polar angle representations around at least a portion of said triangle and having as an axis the center thereof, said triangle having indicia along its sides and grid lines extending perpendicularly inwardly from at least two of its sides, the midpoint of each of the sides indicating an origin point, a first side having an indication of positive indicia to the right of the origin and negative indicia to the left of the origin, and a second side having an indication of negative indicia therealong adjacent to the first side and positive indicia extending from the origin point downwardly, said polar indicia having an origin point at the intersection with a reference line which extends through the axis and is parallel to said first side, and an indicator pivotally mounted on said surface at said axis and having an indicator line adapted to line up said axis with the intersection of any two grid lines and to indicate the polar bearing of said line.

3. An electrocardiograph vector plotter comprising a relatively flat surface, first, second and third triaxial lines represented on said surface and intersecting with each other to form six included angles' of 60 each, polar indicia circumscribing said lines and having as an axis the center thereof, said lines having indicia along their length and grid lines extending perpendicularly from each of the lines, the intersection of the lines indicating origin, the first line having an indication of positive indicia to the right of the origin and negative indicia to the left of the origin and constituting a horizontal reference line, said second and third lines having their positive indicia on the portions thereof which are below said horizontal said horizontal reference line and negative indicia on the portions thereof which are above said horizontal reference line, said polar indicia having an origin point at the intersection with the right side of said horizontal reference line and indicating 0 to minus 180 above said reference line and 0 to plus 180 below said reference line, and an indicator pivotally mounted on said surface at said axis and having an indicator line adapted to line up said axis with the intersection of any two or three grid lines and to indicate the polar bearing of said line.

4. A vector plotter comprising a relatively flat surface, first, second and third triaxial lines represented on said surface and intersecting with each other to form six included angles of 60 each, polar indicia around at least a portion of said lines and having as an axis the center thereof, said lines having indicia along their length and grid lines extending perpendicularly therefrom, the grid lines from one line intersecting those of another line, the midpoint of the lines indicating origin, the first line having an indication of positive indicia to the right of the origin and negative indicia to the left of the origin and constituting a reference line, a second line having positive indicia on the portion thereof which extends downwardly from its origin away from said reference line and negative indicia on the portion thereof which extends upwardly from its origin, said polar indicia having an origin point at the intersection with a line which is parallel with said reference line and coincident with said axis, and an indicator mounted on said surface `and having an indicator line adapted to line up said axis with the intersection of any two of said grid lines and with said polar indicia.

S. An electrocardiograph vector plotter as defined in claim 1, further comprising a relatively second fiat surface, first, second and third triaxial lines represented on said second surface and intersecting with each other to form six included angles of 60 each, polar indicia circumscribing said lines and having as an axis the center thereof, said lines having indicia along their length and grid lines extending perpendiculary from each of the lines, the intersection of the lines indicating origin, the first line having an indication of positive idicia to the right of the orgin and negative indicia to the left of the origin and constituting a horizontal reference line, said second and third lines having their positive indicia on the portions thereof which are below said horizontal reference line and negative indicia on the portions thereof which are above said horizontal reference line, said polar indicia having an origin point at the intersection with the right side of said horizontal reference line and indicating 0 to minus above said reference line and 0 to plus 180 below said reference line, and a second indicator pivotally mounted on said second surface at said axis and having an indicator line adapted to line up said axis with the intersection of any two or three grid lines and to indicate the polar bearing of said line.

References Cited UNITED STATES PATENTS 2,557,428 6/ 1951 Grostic.

2,834,110 5/1958 Malakoff.

2,916,207 12/ 1959 Vohland.

3,374,948 3/1968 McColm 23S-88 WILLIAM D. MARTIN, JR., Primary Examiner U.S. C1. X.R. 35-17; 235-88 

